74hct423pw NXP Semiconductors, 74hct423pw Datasheet - Page 2

• Manufacturer Part Number: 74hct423pw
• Description: Dual Retriggerable Monostable Multivibrator With Reset
• Manufacturer: NXP Semiconductors

Philips Semiconductors
FEATURES
GENERAL DESCRIPTION
The 74HC/HCT423 are high-speed Si-gate CMOS devices
and are pin compatible with low power Schottky TTL
(LSTTL). They are specified in compliance with JEDEC
standard no. 7A.
The 74HC/HCT423 are dual retriggerable monostable
multivibrators with output pulse width control by two
methods. The basic pulse time is programmed by
selection of an external resistor (R
QUICK REFERENCE DATA
GND = 0 V; T
Notes
1. C
2. For HC the condition is V
1998 Jul 08
t
C
t
PHL
W
DC triggered from active HIGH or active LOW inputs
Retriggerable for very long pulses up to 100% duty
factor
Direct reset terminates output pulse
Schmitt-trigger action on all inputs except for the reset
input
Output capability: standard (except for nR
I
I
Dual retriggerable monostable
multivibrator with reset
CC
SYMBOL
f
f
D = duty factor in %
C
V
C
For HCT the condition is V
i
o
/ t
CC
PD
= input frequency in MHz
L
EXT
category: MSI
= output frequency in MHz
(C
PLH
= output load capacitance in pF
P
= supply voltage in V
is used to determine the dynamic power dissipation (P
L
D
= timing capacitance in pF
= C
V
amb
CC
PD
2
propagation delay
input capacitance
minimum output pulse width nQ, nQ
= 25 C; t
nA, nB to nQ, nQ
nR
V
f
o
CC
) = sum of outputs
D
to nQ, nQ
2
f
r
i
PARAMETER
= t
I
I
f
= GND to V
= GND to V
= 6 ns
(C
EXT
L
) and capacitor
V
CC
2
CC
CC
EXT
f
o
)
/C
1.5 V
EXT
0.75
)
C
R
notes 1 and 2
L
EXT
C
= 15 pF; V
2
EXT
= 5 k ; C
(C
connected as shown in Fig.6.
Once triggered, the basic output pulse width may be
extended by retriggering the gated active LOW-going edge
input (nA) or the active HIGH-going edge input (nB). By
repeating this process, the output pulse period
(nQ = HIGH, nQ = LOW) can be made as long as desired.
When nR
nQ output HIGH and also inhibits the triggering.
Figures 7 and 8 illustrate pulse control by reset. The basic
output pulse width is essentially determined by the values
of the external timing components R
For pulse widths, when C
When C
defined as:
t
where, t
Schmitt-trigger action in the nA and nB inputs, makes the
circuit highly tolerant to slower input rise and fall times.
The “423” is identical to the “123” but cannot be triggered
via the reset input.
W
CONDITIONS
D
EXT
= 0.45
in W):
V
CC
). The external resistor and capacitor are normally
R
C
2
CC
EXT
W
EXT
EXT
EXT
D
= pulse width in ns;
= 5 V;
f
is LOW, it forces the nQ output LOW, the
o
R
= external resistor in k ;
= external capacitor in pF.
= 0 pF
EXT
10 000 pF, the typical output pulse width is
D
C
16
EXT
V
25
20
3.5
75
(typ.),
EXT
CC
HC
where:
TYPICAL
10 000 pF, see Fig.9.
74HC/HCT423
Product specification
EXT
26
22
3.5
75
HCT
and C
EXT
ns
ns
pF
ns
.
UNIT